She placed a boombox on the hood of the car, pressed play and stood back.

Silence.

She waited, her breath catching the moonlight as it hit the freezing air and condensed into a trail of fog.

Stars twinkled. A lone frog peeped.

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After a few minutes, the high-pitched, insistent hoot of a northern saw-whet owl rang out from the speakers and became progressively louder, then faded into silence.

With that call, at 1 a.m. on Easter Sunday, Corelyn Senn of Lincolnville began her annual owl monitoring expedition. And it would be her last — at least officially.

The 10-year statewide Maine Owl Monitoring Program wraps up this spring, and along with Senn, volunteers across the state will hang up their clipboards and wait for an analysis of the decade worth of data they’ve collected to be released.

Senn has participated in the program for seven years, annually dedicating one early spring night to monitoring her designated route on the quiet roads of Lincolnville and Belmont.

“What I have enjoyed most is the possibility in it — the possibility, of course, of hearing and seeing owls, but also the unknown possibilities of what one might see and hear in the dark and dense early morning hours,” said Senn, a lifelong wildlife enthusiast who works with autistic children and teens in the midcoast area.

“[Hodgman] had been doing talks about owls and the idea of monitoring owls, and he’d gotten a ton of feedback from people who said they wanted to do it,” Gallo said.

The program’s purpose is “to learn more about the fluctuations in owl populations in our state and to ensure that each species remains an integral part of our ecosystem.”

Maine is home to a variety of owls, including the barn owl, eastern screech owl and snowy owl. The program was created to monitor the more common barred owl, northern saw-whet and great horned owl — sometimes switched out with the long-eared owl.

“It was hugely successful in terms of the number of people who wanted to do the routes, even though the times were crazy,” Gallo said.

Owl monitors choose one night in March or early April to listen for owls at 10 specific stops along their designated route. These nightly monitoring excursions start promptly at 1 a.m. and last until sunrise.

During Senn’s first stop this year, she played the recording — the call of the northern saw-whet, barred and great horned owls, separated by minutes of silence. She waited, hearing nothing but the “peep” of the half-frozen spring peeper, then drove to the next stop.

“It’s an orange lobster buoy on a mailbox, and every year I pray they haven’t changed their mailbox,” she said of the stop.

It wasn’t until her fourth stop, telephone pole 66 at 2 a.m., that she heard her first owl of the night. A barred owl flew up behind her and let out the loud, distinctive call of eight to nine notes that birders describe as “Who cooks for you? Who cooks for you-all?”

She turned and peered into the bare, ghostly branches of birch trees. But as usual, the owl could be heard but not seen. Not that the barred owl couldn’t see us; owls have extremely good night vision.

“It’s pretty neat when it happens,” Senn said in a soft voice as she climbed back in the car.

Since MOMP officially began 2004, 45-85 routes have been monitored each year, depending on volunteer interest. The project almost terminated early in 2008 when the original organizers ran out of funding.

“It’s one of the Catch-22s of citizen science projects. Everyone loves to pay for them to get started, but no one wants to pay for the maintenance in the long term,” Gallo said.

At that time, David Potter, professor of fisheries and aquatic sciences at Unity College, stepped forward.

“I read the message [that MOMP was canceled] and called up and said, ‘I’ll do anything to continue the project because I think it’s worthwhile,’” Potter said.

Since then, MOMP has been in Potter’s hands, though the results are still posted on the Maine Audubon website, maineaudubon.org. Not only does he coordinate the program, he monitors five of the routes.

“The number of professionals [participating] is phenomenally low,” Potter said. “It just doesn’t attract that group. There’s a steam engineer from Skowhegan, there are a few school teachers, and there are lots of women like Corelyn who are just fascinated by owls.”

Gladys Benshimol, a retired teacher from York, has been involved in the project since the beginning, when she saw a newspaper ad calling for volunteers.

“Owls are fascinating. There’s a whole lore and history around owls, and a sort of mythic aura about them —- but I didn’t know really anything about owls. I just loved the concept. The whole idea just seemed quite exciting,” said Benshimol, 61, who monitors a route from Kittery to South Berwick, and while monitoring over the years has seen everything from the expected owls to a curious skunk to a bobcat.

“For me, it’s just magical to be out in the woods at that time,” she said. “You hear all kinds of things, and then if you hear owls, that’s like the icing on the cake.”

What Benshimol has come to enjoy most about the owl project is how it gave her an opportunity to introduce her nieces and nephews, and now grand nieces and nephews, to the great outdoors.

“I just always thought it would just go on and on,” she said. “Maybe I’ll still do it, even if they don’t. Maybe I could sort of have it be a little mission to bring someone new each year to hopefully foster appreciation and enthusiasm into the next generation.”

“None of this stuff seems to attract young people,” Potter said. “But we have this cadre of citizen scientists who aren’t experts but certainly they’re able.”

Citizen science — “projects in which volunteers partner with scientists to answer real-world questions,” as defined by Cornell Lab of Ornithology — are in the works throughout state, such as the Annual Loon Count, for which about 1,000 volunteers travel to Maine’s lakes and ponds in search of loons on the third Saturday of July.

The Maine Audubon currently is seeking volunteers for the Maine Amphibian Monitoring Program, which is a roadside survey that monitors Maine’s nine species of frogs and toads three times a year — early spring, late spring and summer.

“I think it’s a win-win situation,” Gallo said. “For example, with the owl survey, there’s no way we could have trained and paid professionals or consultants to go out and do that work. It would have never happened.”

More and more citizen science opportunities are being offered online. For example, people across the U.S. can submit bird observations on eBird, an online checklist program launched in 2002 by the Cornell Lab of Ornithology and the National Audubon Society that provides data on bird abundance and distribution, provided by birders across the country — or people who simply like to watch their backyard bird feeders.

Similarly, the Maine Audubon Wildlife Road Watch is a Web-based map and database designed to record people’s observations of roadside and road-killed wildlife.

Citizen science not only allows for data to be collected across large geographical regions, it also allows for long-term data collection, which helps scientists understand changes in populations over time.

There is no set date for the final analysis of MOMP to be released, but Potter plans to publish it through the Maine Audubon website and perhaps a scientific journal.

“We have some good data,” Potter said. “If we were to do this again in 20 years, we compare it to the data of these 10 years.”

Yet there are no prior Maine owl studies in which to compare the current data.

“I think that we will have a reasonably good understanding about where owls are situated across the landscape in Maine where the surveys have been conducted and some idea of the density of the owls in that area,” Potter said. “We also have some idea of population fluctuations. As far as the data show, some years there are lot of owls, and some years there are not nearly as many. So far this year, it seems there are not nearly as many.”

Barred owls are the most common owls to respond to the survey, with saw-whet coming in second. Great horned and long-eared owls were seldom detected. Are their numbers low in Maine, or have they simply not returned from migration yet? Or are they there, just not responding?

“Detectability remains a serious issue,” Potter said.

Last year, Senn didn’t hear any owls during her annual owl monitoring night.

“It’s definitely not for everyone,” Senn said. “Some years, I have had a terrible time finding someone to do it with me. And people think I’m nuts. But if you love it, you’re really committed and excited. I think it’s wonderful that we are offered the opportunity.”

This year, Senn’s elation at hearing the barred owl’s eerie hooting abated as the early morning dragged on and the temperature dropped from 32 to 25. At each stop, Senn set up the boombox, pressed play and waited patiently. At one stop, a deer crashed through the forest and crossed the road, its hooves clicking on the pavement. At another stop, nearby dogs howled incessantly, which Senn anticipated from past years.

At 4:18 a.m., she stopped the car for the ninth time and stepped out into the cold. What first seemed like silence became a blend of soft sounds — water running nearby and a repetitive call, so faint it could have been confused with a thought. Was the call becoming louder or were her ears adjusting to the silence?

It was a northern saw-whet — a small, timid owl that winters in conifers and feeds on mice.

The owl was still calling when Senn packed the boombox back into her car and drove to the last stop, where all nighttime sounds were banished by roosters announcing the sunrise.